编程求以孩子兄弟表示法存储的森林的叶节点数

#include <iostream>
typedef struct node{
    char data;
    struct node * pchild;
    struct node * pbrother;
}node,*pnode;

pnode buynode(char x)
{
    node* tmp=(pnode) malloc(sizeof (node));
    tmp->data=x,tmp->pchild= nullptr,tmp->pbrother= nullptr;
    return tmp;
}
//图为p190页t2的树
pnode build_tree()
{
     pnode root= buynode('A');
     root->pchild= buynode('B');
     root->pchild->pbrother= buynode('C');
     root->pbrother= buynode('D');
     root->pbrother->pchild= buynode('E');
     root->pbrother->pchild->pchild= buynode('F');
     root->pbrother->pbrother= buynode('G');
    root->pbrother->pbrother->pchild= buynode('H');
    root->pbrother->pbrother->pchild->pbrother= buynode('I');
    root->pbrother->pbrother->pchild->pbrother->pbrother= buynode('J');
    root->pbrother->pbrother->pchild->pbrother->pbrother->pchild= buynode('M');
    root->pbrother->pbrother->pchild->pbrother->pbrother->pchild->pchild= buynode('P');
    root->pbrother->pbrother->pchild->pbrother->pbrother->pchild->pbrother= buynode('N');
    root->pbrother->pbrother->pchild->pbrother->pbrother->pchild->pbrother->pbrother= buynode('O');
    root->pbrother->pbrother->pchild->pchild= buynode('K');
    root->pbrother->pbrother->pchild->pchild->pbrother= buynode('L');
    return root;
}

int leaves(pnode root)
{
    if(root== nullptr) return 0;
    if(root->pchild== nullptr) {
        printf("%3c", root->data);
        return 1 + leaves(root->pbrother);
    }
    else return leaves(root->pchild)+leaves(root->pbrother);
}
int main() {
    pnode root=build_tree();
    printf("the leaves are:");
    printf("%3d\n", leaves(root));
    return 0;
}